Abstract

The combined effects of salinity and water logging on growth and ecophysiological characteristics of three Melaleuca species were investigated in a glasshouse study. Salinity treatments were imposed from day 28 at 0.3, 0.8, 2 and 5 g NaCl kg^-1 soil. Shoot Na⁺ concentration and Na⁺/K⁺ratio for M. thyiodes at all salt level and of M. nesophila at 5.0 g NaCl kg^-1 were higher under waterlogged as compared with non-waterlogged conditions. The concentration of Cl^- was double inM. thyiodes and M. nesophila shoots after 2 weeks of water logging at 5 g NaCl kg^-1 soil, but not inM. halmaturorum. Final dry weights of shoots and roots of the three Melaleuca species decreased with increased salinity levels. Shoot dry weight of plants grown at 5.0 g NaCl kg^-1 soil decreased to 30, 50 and 11% of those achieved at 0.3 g NaCl kg^-1 soil for M. halmaturorum, M. thyoides, and M. nesophila, respectively. The results indicated different salinity resistance within Melaleuca species.

Key words: Sodium, potassium, chloride, Na⁺/K⁺ ratio, water logging.